1. Field of the Invention
This invention relates to a cultivating machine and more particularly, although not exclusively to a cultivating machine of the type used to cultivate turf such as used for golf courses, sports arenas, bowling greens and the like. More specifically, the invention is concerned with a cultivating machine of the type described in Australian Patent Application No. 73500/87.
2. Description of the Prior Art
The specification of the aforementioned Patent Application describes a machine having a wheeled frame on which is mounted a tool support means. The tool support means is power driven and carries a cultivating tool, and the manner in which the support means is driven causes the cultivating tool to reciprocate in a substantially vertical plane. When the machine is moved along the ground in use the cultivating tool is caused to repeatedly penetrate the ground thereby aerating and improving the condition of the ground. The specification of Patent Application No. 73500/87 is included herein by way of reference.
It will be appreciated that repeated penetration of the ground by the cultivating tool will place a substantial strain on the components and linkages which comprise the machine. This is particularly so where the machine is used over hard ground or where the cultivating tool strikes a sub-surface rock or the like. Machines manufactured in accordance with the aforementioned specification have in operational conditions had components breaking during use which causes delay and can be costly.
A similar type of machine is described in Australian Patent Application 41609/89. This machine is less susceptible to damage during use, but does not make a fully satisfactory hole in the ground. For general purposes, the edges of a hole made by a cultivating machine need not be particularly even; the length of the grass or turf is such that a hole with rough edges or a slightly larger hole than the hole making tool is unimportant. However, on golfing or bowling greens and the like where the vegetation is short, a hole with rough edges or too large a hole can cause spot erosion, resulting in an undesirable dimple in the ground surface. This effect is aggravated when the forward movement of a cultivator is faster than the speed of the hole making tool over the ground, causing the hole making tool to "rake" the ground surface. Since some cultivators are powered by a link to a prime mover, such as a tractor, it is very hard to synchronise the speed of the hole making tool with the speed of the tractor, given the different gear ratios between the driving wheels of the tractor and the power link. This tends to aggravate any problem in forming neat holes.
To ensure as neat a hole as possible, it is important that the tines of the hole making tool remain as near to vertical as possible whilst they are in contact with the ground. One means of achieving this is depicted in Australian Patent Application 41609/89 wherein a hole making tool is attached to one end of support means, the other end of the support means being driven in a circular motion by drive means. The support means is kept substantially vertical by a rigid link near the hole making tool, wherein the link is pivotably connected to both the support means and the frame of the cultivating machine. As previously mentioned, this type of machine was not entirely satisfactory for applications where a neat hole is required.
A similar type of machine is also depicted in U.S. Pat. Nos. 4,753,298 and 4,867,244. In these machines, a pivotable rigid link is connected between the support means and a swing arm pivotably connected to the frame of the machine, allowing for greater variation in the forward speed of the cultivator over the ground compared with the forward speed of the hole making tool. In these machines the swing arms are linked in pairs, either by further links to a rocker shaft or by intermeshing teeth adjacent the pivot of each swing arm with the machine frame, so that adjacent pairs of hole making tools are linked to reciprocate forward and back as alternate tools contact the ground. Besides being mechanically more complex and therefore more expensive to produce and more liable to break downs, these machines also create a less than satisfactory hole.
The present invention aims to alleviate or overcome one or more of the aforementioned disadvantages.